CONTRIBUTIONS TO PALEONTOLOGY. 101 



the front, which is obtusely rounded : the border in front of the glabella 

 is deeply concave, and rises to the margin, which is thickened and striated. 

 Geological formation arid locality. In the upper limestone of the Upper 

 Helderberg group : at Williamsville and other places in Western New- 

 York , in Canada West ; in Ohio, and at the Falls of the Ohio. 



PROETUS CANALICULATUS (n.s.). 



A fragment of this species, preserving the glabella, presents characters 

 distinguishing it from any other in these rocks. The glabella is convex, ovoid, 

 width and length about as five to six ; somewhat abruptly contracted op- 

 posite the anterior angles of the eye, and again a little spreading before 

 curving ,tQ.-the. anterior margin. The anterior glabella-furrow is short, and 

 curves gently backwards : the second furrow begins at the anterior angle 

 of the eye. is longer, and curves backwards ; while the third furrow origi- 

 nates opposite the centre of the eye, is nearly rectangular to the axis for a 

 short distance, and then bends abruptly backwards, reaching nearly to the 

 base of the glabella : at the centre of the base of the glabella there is a 

 little prominence, and a slight depression on each side, while the posterior 

 angles are subtruncate. Occipital furrow narrow, with an occipital ring of 

 moderate strength. At the anterior margin of the glabella, the limb is 

 marked by a sharp furrow, which is margined by a slight elevation ; be- 

 yond which it is regularly concave to a narrow ridge, and between this and 

 the outer margin is a narrow even groove. Surface finely granulose. 



The last-mentioned groove, the form of the glabella, and the peculiarity 

 of the posterior glabellar furrow, are distinguishing features. 



Geological formation and locality. In limestone of the age of the Upper 

 Helderberg group : at the Falls of the Ohio. 



PROETUS VERNEUILI (n.s.). 



An entire specimen, which has the anterior part of the thorax and head 

 crushed and distorted, presents peculiar and distinguishing characters in the 

 P3^gidium. The glabella is small and very prominent ; the border is a little 

 concave, and much extended in front. The thorax is comparatively small ; 

 the axis very prominent^ a little compressed on the sides : lateral lobes 

 somewhat flattened near the axis, and curving abruptly downwards. Pygi- 

 dium proportionally large, width nearly once and a half the length : axis 

 prominent, a little compressed on the sides, marked by eleven rings, which 

 are direct from the base, but bent backwards, and are a little thickened in 

 the middle ; the second from the anterior margin, shows the base of a small 

 spine : lateral lobes a little depressed at the dorsal furrow, and regularly 

 convex beyond, marked by eight rounded ribs which are deeply sulcata be- 

 1861.] 



